title: Skeletal muscle morphology and risk of cardiovascular disease in elderly men.
abstract: BACKGROUND
  While it is well known that physical inactivity is a major risk factor for cardiovascular disease, there is still a search for the mechanisms by which exercise exerts its positive effect. Skeletal muscle fibre type can be affected to some extent by exercise, and different fibre types possess different anti-inflammatory and glucometabolic properties that may influence cardiovascular disease risk.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  We investigated relations of skeletal muscle morphology to risk of cardiovascular events in a sample of 466 71-year-old men without cardiovascular disease, of which 295 were physically active (strenuous physical activity at least 3 h/week).
  
  
  RESULTS
  During a median of 13.1 years of follow up, 173 major cardiovascular events occurred. Among physically active men, 10% higher proportion of type-I (slow-twitch oxidative) fibres was associated with a hazard ratio (HR) of 0.84 (95% confidence interval 0.74-0.95) for cardiovascular events, and 10% higher proportion of type-IIx (fast-twitch glycolytic) fibres was associated with a HR of 1.24 (1.06-1.45), adjusting for age. Similar results were observed in several sets of multivariable-adjusted models. No association of muscle fibre type with risk of cardiovascular events was observed among physically inactive men.
  
  
  CONCLUSIONS
  Higher skeletal muscle proportion of type-I fibres was associated with lower risk of cardiovascular events and a higher proportion of type-IIx fibres was associated with higher risk of cardiovascular events. These relations were only observed in physically active men. Skeletal muscle fibre composition may be a mediator of the protective effects of exercise against cardiovascular disease.
authors.affiliation: Uppsala University, Uppsala, Sweden kasper.andersen@medsci.uu.se.
authors.forename: Kasper
authors.initials: K
authors.lastname: Andersen
authors.affiliation: Uppsala University, Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Lind
authors.affiliation: Uppsala University, Uppsala, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Ingelsson
authors.affiliation: Uppsala University, Uppsala, Sweden Högskolan Dalarna, Falun, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Ärnlöv
authors.affiliation: Uppsala University, Uppsala, Sweden.
authors.forename: Liisa
authors.initials: L
authors.lastname: Byberg
authors.affiliation: Uppsala University, Uppsala, Sweden.
authors.forename: Karl
authors.initials: K
authors.lastname: Michaëlsson
authors.affiliation: Uppsala University, Uppsala, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Sundström
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D015331:Cohort Studies; D016207:Cytokines / Q000009:adverse effects; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology*
chemical_list: D016207:Cytokines
keywords: Cardiovascular diseases; cytokines; insulin resistance; physical activity; skeletal muscle fibres